Submitted to: International Congress of Mycology Proceedings and Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 3/28/1998
Publication Date: N/A
Technical Abstract: In experiments with species of Puccinia and Uromyces from hosts in the Graminae, nectar transferred between pycnia of opposite mating type (as indicated by subsequent aecia formation) induced formation of a cap on one end of pycniospores, starting within 10-30 min. Caps were induced equally in reciprocal nectar transfers. In addition, transfer of nectar from pycnia of one species to another induced caps in patterns suggesting that mating type could be recognized between the species, although aecia were not produced. The caps were stained by India ink, colloidal gold, or wheat germ agglutinin conjugated with FITC. Caps were removed by treatment with Proteinase K or Novozyme, suggesting that caps contain chitin or its oligomers and protein. Cap-inducing activity was lost if nectar was boiled or autoclaved. With nectar run on native PAGE gels, inducing activity was present in protein bands in a region extending from the origin to about 132 2kDa. In SDS gels, multiple polypeptide bands ranging from 14-62 kDa were observed, but bioassays of these polypeptides for cap induction were not successful. The results indicate that pycnial nectar contains pheromone-like proteins which are mating type-specific and induce pycniospore cap formation as an initial event preceding fusion of pycniospores with receptive hyphae.